The present invention relates to the field of constructions, assemblies and systems designed to thermally insulate and seal a sating slot area defined between a curtain wall and the individual floors of a building. In particular, the present invention relates to a fire-resistance-rated thermally insulating and sealing system for use with curtain wall structures which include glass, especially vision glass extending to the finished floor level below.
Curtain walls are generally used and applied in modern building constructions and are the outer covering of the constructions in which the outer walls are non-structural, but merely keep the weather out and the occupants in. Curtain walls are usually made of a lightweight material, reducing construction costs and weight. When glass is used as the curtain wall, a great advantage is that natural light can penetrate deeper within the building.
A curtain wall generally transfers horizontal wind loads that are incident upon it to the main building structure through connections at floors or columns of the building. Curtain walls are designed to resist air and water infiltration, sway induced by wind and seismic forces acting on the building and its own dead load weight forces. Curtain walls differ from store-front systems in that they are designed to span multiple floors, and take into consideration design requirements such as thermal expansion and contraction, building sway and movement, water diversion, and thermal efficiency for cost-effective heating, cooling, and lighting in the building.
However, architects and the public at large appreciate the aesthetics of glass and other light-transmitting materials used in the built environment. Light-transmitting materials, that serve both an aesthetic function as well as a structural function, are appreciated for their economy and visual effects. A common means prescribed by architects to achieve these goals in building structures is through the use of glass curtain wall systems.
A typical glass curtain wall structure is designed with extruded aluminum members. The aluminum frame is typically infilled with glass, which provides an architecturally pleasing building, as well as benefits such as daylighting. Usually, for commercial construction, ¼ inch glass is used only in spandrel areas, while 1 inch insulating glass is used for the rest of the building. In residential construction, thicknesses commonly used are ⅛ inch glass in spandrel areas and ⅝ inch glass as insulating glass. Larger thicknesses are typically employed for buildings or areas with higher thermal, relative humidity, or sound transmission requirements, such as laboratory areas or recording studios.
With a curtain wall, any glass may be used which can be transparent, translucent, or opaque, or in varying degrees thereof. Transparent glass usually refers to vision glass in a curtain wall. Spandrel or vision glass may also contain translucent glass, which could be for security or aesthetic purposes. Opaque glass is used in areas to hide a column or spandrel beam or shear wall behind the curtain wall. Another method of hiding spandrel areas is through shadow box construction, i.e. providing a dark enclosed space behind the transparent or translucent glass. Shadow box construction creates a perception of depth behind the glass that is sometimes desired. Aesthetic design and performance levels of curtain walls can be extremely varied. Frame system widths, depths, anchoring methods, and accessories have grown diverse due to industry and design innovation.
In general, a glass curtain wall structure or glass curtain wall construction is defined by an interior wall glass surface including one or more framing members and at least one floor spatially disposed from the interior wall surface. The gap between the floor and the interior wall surface of a curtain wall defines a safing slot, also referred to as perimeter slab edge (void), extending between the interior wall surface of the curtain wall construction and the outer edge of the floor. This safing slot is essential to slow the passage of fire and combustion gases between floors. Therefore, it is of great importance to improve firestopping at the safing slot in order to keep heat, smoke and flames from spreading from one floor to an adjacent floor. It is important to note that the firestop at the perimeter slab edge is considered a continuation of the fire-resistance rating of the floor slab. The curtain wall itself, however, is not ordinarily required to have a rating. Conversely, a glass curtain wall, including extruded aluminum members, is rated as 0 hours and the standard fire test method NFPA 285 is not needed due to non-combustible materials. NFPA 285 generally provides a standardized fire test procedure for evaluating the suitability of exterior, non-load bearing wall assemblies and panels used as components of curtain wall assemblies, and that are constructed using combustible materials or that incorporate combustible components for installation on buildings where the exterior walls are required to be non-combustible.
In order to obtain certified materials, systems and assemblies used for structural fire-resistance and separation of adjacent spaces to safeguard against the spread of fire and smoke within a building and the spread of fire to or from the building, the International Building Code IBC 2012 provides minimum requirements to safeguard the public health, safety and general welfare of the occupants of new and existing buildings and structures. According to the International Building Code IBC 2012 Section 715.4, voids created at the intersection of the exterior curtain wall assemblies and such floor assemblies shall be sealed with an approved system to prevent the interior spread of fire where fire-resistance-rated floor or floor/ceiling assemblies are required. Such systems shall be securely installed and tested in accordance with ASTM E 2307 to provide an F rating for a time period at least equal to the fire-resistance-rating of the floor assembly.
However, there is a code exception that states that voids created at the intersection of the exterior curtain wall assemblies and such floor assemblies, where the vision glass extends to the finished floor level, shall be permitted to be sealed with an approved material to prevent interior spread of fire. Such material shall be securely installed and capable of preventing the passage of flame and hot gasses sufficient to ignite cotton waste when subjected to ASTM E 119 time-temperature fire conditions under a minimum positive pressure differential of 0.01 inch of water column for the time period at least equal to the fire-resistance rating of the floor assembly.
Although some glass and frame technologies have been developed that are capable of passing applicable fire test and building code requirements, there is no system that addresses the exception stated in the International Building Code IBC 2012 Section 715.4 and fulfills the code section ASTM E 2307 full-scale testing.
Due to the increasingly strict requirements regarding fire-resistance, there is a need for a thermally insulating and sealing system for glass curtain wall structure that is capable of meeting or exceeding existing fire test and building code requirements including existing exceptions. In particular, there is a need for systems that prevent the spread of fire when vision glass of a curtain wall structure extends to the finished floor level below. Further, there is a need for systems that address the architectural limitation of the width of a column or spandrel beam or shear wall behind the curtain wall. Additionally, maintaining safing insulation between the floors of a residential or commercial building and the exterior curtain wall responsive to various conditions including fire exposure should be guaranteed.
In view of the above, it is an object of the present invention to provide an offset leg framing element for use in a fire-resistance rated curtain wall construction defined by an interior wall surface including one or more framing members and at least one floor spatially disposed from the interior wall surface of the curtain wall construction, wherein the vision glass of a curtain wall structure extends to the finished floor level below.
Further, it is an object of the present invention to provide a thermally insulating and sealing system for effectively thermally insulating and sealing of a safing slot within a building construction, having a curtain wall construction defined by an interior wall surface including one or more framing members and at least one floor spatially disposed from the interior wall surface of the curtain wall construction, wherein the vision glass of a curtain wall structure extends to the finished floor level below.
Still further, it is an object of the present invention to provide a full-scale ASTM E 2307 tested system for floor assemblies where the vision glass extends to the finished floor level, to address the code exception, to avoid letters and engineering judgments, and to secure and provide defined/tested architectural detail for this application, in particular by providing a tested system for fire safe architectural compartmentation.
Still further, it is an object of the present invention to provide a tested system that provides for integrated and unexposed mullion covers whose thickness ends at the bottom of the floor surface for maximum vision glass exposure. The tested system utilizes no aluminum or faced curtain wall insulation, and the safing insulation can be pre-installed from one side, which maintains the safing insulation between the floors of a residential or commercial building and the glass curtain wall responsive to various conditions, including fire exposure, and maximizes safing insulation at a minimal cost.
Still further, it is an object of the present invention to provide a building construction comprising of such a thermally insulating and sealing system for effectively thermally insulating and sealing of the safing slot between a glass curtain wall structure and the edge of a floor, in particular within the zero spandrel area, wherein the vision glass of a curtain wall structure extends to the finished floor level below.
These and other objectives as they will become apparent from the ensuring description of the invention are solved by the present invention as described in the independent claims. The dependent claims pertain to preferred embodiments.
In one aspect, the present invention provides an offset leg framing element for use in a fire-resistance rated curtain wall construction defined by an interior wall surface including one or more framing members and at least one floor spatially disposed from the interior wall surface of the curtain wall construction, wherein vision glass extends to the finished floor level below, comprising a web section having opposing edges; a pair of outwardly extending sidewalls integrally connected to the web section, wherein each sidewall has a proximal end and a distal end, wherein the proximal end of each sidewall is integrally connected to one of the opposing edges of the web section, and wherein the sidewalls are substantially parallel and confront each other; and optionally one laterally extending ledge section integrally connected to one of the pair of outwardly extending sidewalls, wherein the ledge section has an inner edge and an outer edge, and wherein the inner edge of the ledge section is integrally connected to the distal end of one of the pair of sidewalls.
In another aspect, the present invention provides a thermally insulating and sealing system for effectively thermally insulating and sealing of a safing slot within a building construction having a curtain wall construction defined by an interior wall surface including one or more framing members and at least one floor spatially disposed from the interior wall surface of the curtain wall construction defining the safing slot extending between the interior wall surface of the curtain wall construction and an outer edge of the floor, wherein vision glass extends to the finished floor level below, comprising a first element comprised of a thermally resistant material for insulating positioned in the safing slot, wherein the first element includes an inner primary end surface positionable in abutment with respect to the outer edge of the floor for sealing thereadjacent, an outer primary end surface positionable spatially disposed from the interior wall surface of the curtain wall construction, lower primary facing surface extending between the inner primary end surface and the outer primary end surface and facing downwardly therebetween; a second element comprised of a non-combustible material for receiving the first element positioned substantially in the safing slot in abutment with respect to the bottom of the floor and essentially spatially disposed from the interior wall surface, wherein the second element includes a web section having opposing edges; a pair of outwardly extending sidewalls integrally connected to the web section, wherein each sidewall has a proximal end and a distal end, wherein the proximal end of each sidewall is integrally connected to one of the opposing edges of the web section, and wherein the sidewalls are substantially parallel and confront each other; and optionally one laterally extending ledge section integrally connected to one of the pair of outwardly extending sidewalls, wherein the ledge section has an inner edge and an outer edge, and wherein the inner edge of the ledge section is integrally connected to the distal end of one of the pair of sidewalls; and a supplemental element for attaching of the second element with respect to the bottom of the floor.
In yet another aspect, the present invention provides a building construction comprising the thermally insulating and sealing system.
The subject matter of the present invention is further described in more detail by reference to the following figures.